Page 669 - The Veterinary Care of the Horse

cysts and tumours are also visible on the radiographs.

When a tooth root is infected, it may be possible to see erosion of bone or areas of
VetBooks.ir increased bone density around the apex of the tooth. The affected root may have been eroded

by the infection and have an altered outline. With dental disease a fluid line may or may not
be visible.

ENDOSCOPY

This is done in two ways. By passing the endoscope up the nasal passages, the vet will try to
locate the source of the discharge. The drainage opening (ostia) of the sinuses can be seen

and checked for abnormalities. Sometimes pus or blood can be seen trickling from them. The
vet will also check for any narrowing or ulceration of the nasal passages. If an ethmoid
haematoma is the cause of the sinusitis, it can usually be seen with an endoscope.

Alternatively, sinus endoscopy may be performed. The endoscope is inserted directly into

the sinus through a hole (trephine) drilled in the overlying bone. The sinus cavity can then be
inspected.

BIOPSY

The results of the radiography and endoscopy may suggest the presence of a cyst or tumour.
In this case, exploratory surgery and biopsy may be performed. If the sinus cavity has not
already been opened, a small hole is made in the overlying bone. Samples of the pus or

abnormal tissue can be taken for culture and examination under the microscope. This can be
done under sedation using local anaesthetic.

Treatment

• A sinus infection that develops following an upper respiratory tract infection usually
responds well to antibiotics if treated promptly. Mucolytics and steam inhalation can help

to shift the mucopus and restore the normal mucociliary clearance mechanisms. Light
exercise should be continued. If the nasal discharge returns when the antibiotics are

finished, further investigation is necessary.
• If the discharge persists, an in-dwelling catheter may be inserted into the sinus through a

small hole. The sinus is flushed regularly for 1–2 weeks with large volumes of lukewarm
saline, dilute antiseptics and/or antibiotics to clear the mucus and eliminate infection.

During this time, light exercise is beneficial
• In chronic cases where the pus has become very solid, surgery may be necessary to

remove it. This is done through a bone flap made in the horse’s face while under standing